Processing with system modeling, simulation and optimization algotithm, this book bases on the macro introduction to various thoeries and methods of system modeling, system simulation and system optimization related to computer simulation technology. With MATLAB and PSpice Simulation technology which is currently widely used in power electronic research field, this book introduces MATLAB software and the basic application knowledge of its graphic simulation interface-Simulink, as well as foundations of PSpice Simulation technology. Through the application cases of the power electronic devices and DC-DC transformation, AC-DC transformation and DC-AC transformation, this book also compares and shows the technology and methods of power electronic circuit simulation based on MATLAB and PSpice.